Construct a Circular Polygon Feature

I'm looking to create a circular polygon feature using the ArcObjects .NET API. I basically want to read a list of points and diameters from a text file, then draw the circles and save them to a polygon feature class. I've been pouring through the documentation on ICircularArc and plenty of other Interfaces, but I can't seem to find what I'm looking for. The closest thing I've done is draw a circular line using the following code sample.